EP3013128A1 - Flexible printed circuit board and method of manufacturing the same - Google Patents
Flexible printed circuit board and method of manufacturing the same Download PDFInfo
- Publication number
- EP3013128A1 EP3013128A1 EP15197991.1A EP15197991A EP3013128A1 EP 3013128 A1 EP3013128 A1 EP 3013128A1 EP 15197991 A EP15197991 A EP 15197991A EP 3013128 A1 EP3013128 A1 EP 3013128A1
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- EP
- European Patent Office
- Prior art keywords
- printed circuit
- flexible printed
- partial
- component mounting
- circuit board
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/11—Printed elements for providing electric connections to or between printed circuits
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/14—Structural association of two or more printed circuits
- H05K1/142—Arrangements of planar printed circuit boards in the same plane, e.g. auxiliary printed circuit insert mounted in a main printed circuit
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0277—Bendability or stretchability details
- H05K1/028—Bending or folding regions of flexible printed circuits
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/03—Use of materials for the substrate
- H05K1/0313—Organic insulating material
- H05K1/032—Organic insulating material consisting of one material
- H05K1/0346—Organic insulating material consisting of one material containing N
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/0097—Processing two or more printed circuits simultaneously, e.g. made from a common substrate, or temporarily stacked circuit boards
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/36—Assembling printed circuits with other printed circuits
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/36—Assembling printed circuits with other printed circuits
- H05K3/361—Assembling flexible printed circuits with other printed circuits
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/11—Printed elements for providing electric connections to or between printed circuits
- H05K1/118—Printed elements for providing electric connections to or between printed circuits specially for flexible printed circuits, e.g. using folded portions
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/05—Flexible printed circuits [FPCs]
- H05K2201/052—Branched
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/49117—Conductor or circuit manufacturing
- Y10T29/49124—On flat or curved insulated base, e.g., printed circuit, etc.
- Y10T29/49126—Assembling bases
Abstract
Description
- The present invention relates to a printed circuit board and a method of manufacturing the same, and more particularly, to a flexible printed circuit board having a plurality of cable sections that extend in different directions from a component mounting section for mounting an electronic component and a method of manufacturing the same.
- In recent years, electronic components have been becoming more and more miniaturized and high functional. For this reason, demands for a densified printed circuit board or an electronic component mounted thereon are increasing. Particularly, in a package component used in a portable device, for example a chip size package (CSP), the number of pins increases, and a pitch between pins is getting narrow. For example, in the case of a sensor module in which many sensors are integrated, the number of pins is proportional to the number of sensors, and the number of pins ranges from several hundreds to several thousands. Further, a pitch between pins has gotten narrow up to about 500 µm.
- As a flexible printed circuit board that is advantageous in mounting a package component having many pins and a narrow pitch such as the CSP, a so-called step via structure has been known (for example, Patent Document 1). The overall manufacturing method thereof is as follows.
- First, a fine wiring is formed on a core substrate that is an inner layer, and thereafter a build-up layer that is an outer layer is stacked on the core substrate. A step via hole of a step form composed of an upper hole having a large diameter and a lower hole having a small diameter is formed by a conformal laser process. Thereafter, a plating process is performed on an inner wall of the step via hole, so that a step via functioning as an interlayer conductive path is formed. By employing the step via structure, a wiring of the outer layer can be miniaturized, and thus a flexible printed circuit board that is advantageous in mounting a package component having many pins and a narrow pitch can be obtained.
- However, in the case of the above described sensor module, the pins of the sensor module are installed to output signals of the sensors associated with the pins. For this reason, the flexible printed circuit board for mounting the sensor module needs to have many fine wirings for electrically connecting the pins of the sensor module to terminals installed in a contact section connected with an external device. Further, according to a use form of the flexible printed circuit board, there is a case in which it is necessary to draw out a plurality of cable sections including the wirings in different directions from a mounting area of an electric component. An example of such a flexible printed circuit board will be described in detail with reference to the drawings.
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FIG. 7(1) is a plan view of a conventional flexible printedwriting board 44 on which an electronic component having many pins with a narrow pitch are mounted.FIG. 7(2) is a cross-sectional view taken along line A-A ofFIG. 7(1) . However, these drawings do not illustrate an internal structure of acomponent mounting section 41. - As illustrated in
FIG. 7(1) , the flexibleprinted circuit board 44 includes acomponent mounting section 41 for mounting an electronic component thereon, a plurality offlexible cable sections 42 respectively extending in up, down, right, and left directions from thecomponent mounting section 41, andconnection sections 43 respectively installed at forefronts of theflexible cable sections 42. - The
component mounting section 41 has a plurality oflands 41a for being bonded with pins of the electronic component such as a sensor module. - The
flexible cable section 42 has flexibility and extends in a predetermined direction from thecomponent mounting section 41. Further, theflexible cable section 42 has a plurality of fine wirings (not shown) for electrically connecting theland 41a with aterminal 43a of theconnection section 43. - The
connection section 43 has a plurality ofterminals 43a for a connection with an external device. - Each of the plurality of
terminals 43a is electrically connected with theland 41a corresponding thereto through the wiring of theflexible cable section 42. - Next, a state in which an electronic component is mounted on the flexible printed
circuit board 44 will be described with reference toFIG. 8 . -
FIG. 8(1) is an enlarged plan view of thecomponent mounting section 41 on which anelectronic component 45 is mounted, andFIG. 8(2) is a cross-sectional view taken along line A-A ofFIG. 8(1) . As illustrated inFIG. 8(2) , a pin (solder ball) 45a of theelectronic component 45 is bonded with acorresponding land 41a of thecomponent mounting section 41. - As can be seen from
FIG. 8(2) , awiring 46 for electrically connecting theland 41a with theterminal 43a is installed betweenstep vias - The
electronic component 45 is, for example, a sensor module, and in this case, a signal of a sensor included in the sensor module is output from thepin 45a and transmitted to theterminal 43a through theland 41a, the step via 47, and thewiring 46. - Incidentally, in an actual process of manufacturing a flexible printed circuit board, a sheet of a predetermined size comparting a long material (for example, a copper-clad laminated sheet having a copper foil on an insulating film) is used as a process target unit of various processes. Thus, manufacturing is performed in a state in which a plurality of flexible printed circuit boards are arranged in a sheet according to a predetermined layout. How to arrange the flexible printed circuit boards in the sheet (i.e., a sheet layout) is decided in advance.
FIG. 9 is a plan view of asheet 48 having 9 flexible printedcircuit boards 44 manufactured according to a predetermined layout. - As can be seen from
FIG. 9 , since the area of the flexible printedcircuit board 44 is large and theflexible cable sections 42 are installed to extend in up, down, right, and left directions from thecomponent mounting section 41, a degree of freedom of the sheet layout is limited, and it is difficult to arrange the flexible printed circuit board 44s in a more efficient fashion within thesheet 48. - As described above, in the past, it was impossible to achieve the efficient sheet layout due to the restriction attributable to the outer shape of the flexible printed circuit board or the like. As a result, it has been difficult to reduce the manufacturing cost of the flexible printed circuit board.
- Further, in the past, in addition to the above described sheet layout problem, there has been a problem that a yield decreases due to a wiring failure. This will be described using an example of the flexible printed
circuit board 44. As described above, a plurality ofwirings 46 are installed between thestep vias 47, but since theelectronic component 45 has significantly many pins, a pitch of thewiring 46 becomes finer to the most extent as a wiring pitch installed in the flexible printedcircuit board 44. For example, when an interval ofinner layer lands 41b installed on the same layer as thewiring 46 is 200 µm and 6 wirings are installed between theinner layer lands 41b as illustrated inFIG. 8(2) , the wiring pitch is just about 30 µm. It is necessary to form a fine wiring pitch for a wiring pitch in theflexible cable section 42 as well as thecomponent mounting section 41. - In forming a wiring, when a foreign substance whose size is almost equal to or more than an interval between wirings sticks to a wiring area or an exposure mask, a wiring failure occurs. For this reason, the larger the wiring area is, the higher the probability that wiring failure will be caused by sticking of the foreign substance is, and thus the lower the yield is.
- As described above, an area of the flexible printed
circuit board 44 in which the fine wiring ranges over theflexible cable section 42 as well as thecomponent mounting section 41. It is not actually easy to form the fine wiring in an area having the relatively large area size without any defect, and thus a reduction in the yield has been unavoidable in the related art. - The problems of the related art have been described in connection with the example of the multi-layer flexible printed circuit board having the step via structure, but the above problems of the sheet layout and the yield are not caused by the step via structure or the multi-layer structure.
- Further, a technique related to a so-called replacement substrate has been disclosed in the past (
Patent Document 2 and Patent Document 3). When a failure occurs on an aggregated substrate composed of a plurality of unit substrates, by selectively replacing a defective unit substrate with a good one, the aggregated substrate becomes a good product. Thus, it can be understood that the above-described problem cannot be solved by this technique. -
- Patent Document 1: Japanese Patent Application Laid-Open (
JP-A) No. 2007-128970 - Patent Document 2: Japanese Patent Application Laid-Open (
JP-A) No. 2008-235745 - Patent Document 3: Japanese Patent Application Laid-Open (
JP-A) No. 2010-40949 - An object of the present invention is to allow an efficient sheet layout and thus to improve the yield in manufacturing a flexible printed circuit board having a plurality of cable sections that extend in different directions from a component mounting section.
- According to a first aspect of the present invention, a method of manufacturing a flexible printed circuit board is provided which includes a component mounting section for mounting an electronic component and a plurality of flexible cable sections extending in different directions from the component mounting section, the method including manufacturing a plurality of partial flexible printed circuit boards in a predetermined sheet in a unit of the partial flexible printed circuit board including a partial component mounting section formed by dividing the component mounting section into the predetermined number of parts and a flexible cable section extending from the partial component mounting section among the plurality of flexible cable sections, cutting an area including the partial flexible printed circuit board away from the sheet, performing a positional alignment of the predetermined number of partial flexible printed circuit boards such that the predetermined number of partial component mounting sections are combined to configure the component mounting section, and fixing the predetermined number of aligned partial flexible printed circuit boards to a support plate.
- According to a second aspect of the present invention, a flexible printed circuit board is provided which includes a predetermined number of partial flexible printed circuit boards, each of which includes a partial component mounting section formed by dividing a component mounting section for mounting an electronic component into the predetermined number of parts and a flexible cable section extending from the partial component mounting section, and a support plate which fixes the predetermined number of partial flexible printed circuit boards in such a manner that the predetermined number of partial component mounting sections are combined to configure the component mounting section.
- According to a third aspect of the present invention, a method of manufacturing a flexible printed circuit board is provided which includes manufacturing a plurality of first partial flexible printed circuit boards, each including a first partial component mounting section having a first land formed on a surface thereof and a flexible cable section extending from the first partial component mounting section, manufacturing a plurality of second partial flexible printed circuit boards, each including a second partial component mounting section having a second land formed on a surface thereof and an interlayer conduction path electrically connected with the second land and a flexible cable section extending from the second partial component mounting section, forming a lower flexible printed circuit board by performing an positional alignment so that the first partial component mounting sections of the two first partial flexible printed circuit board can configure a lower component mounting section and then fixing the two first partial flexible printed circuit boards onto a support plate, forming an upper flexible printed circuit board by performing a positional alignment so that the second partial component mounting sections of the two second partial flexible printed circuit board can configure an upper component mounting section and then fixing the two second partial flexible printed circuit boards onto an anisotropic conductive film containing a conductive particle, and forming a component mounting section including the upper component mounting section and the lower component mounting section in which the first land is electrically connected with the second land positioned directly thereon through the conductive particle and the interlayer conduction path by placing the upper flexible printed circuit board on the lower flexible printed circuit board and applying heat and pressure thereto.
- According to a fourth aspect of the present invention, a flexible printed circuit board is provided which includes: a support plate; a first partial flexible printed circuit board including a first partial component mounting section having a first land formed on a surface thereof and a first interlayer conduction path electrically connected with the first land, and a flexible cable section extending from the first partial component mounting section; and a second partial flexible printed circuit board including a second partial component mounting section having a second land formed on a surface thereof and a second interlayer conduction path electrically connected with the second land, and a flexible cable section extending from the second partial component mounting section; in which a lower component mounting section configured such that the two first partial component mounting sections are arranged on the same plane is fixed onto the support plate, an upper component mounting section configured such that the two second partial component mounting sections are arranged on the same plane is stacked on the lower component mounting section through an anisotropic conductive layer having a conductive particle therein, and the first land is electrically connected with the second land positioned directly thereon through the conductive particle and the second interlayer conduction path.
- The present invention has the following effects due to these features.
- According to an embodiment of the present invention, a plurality of partial flexible printed circuit boards are manufactured in a sheet on a unit basis, each unit including a partial component mounting section formed by dividing a component mounting section for mounting an electronic component into the predetermined number of parts and a flexible cable section extending from the partial component mounting section. For this reason, the area size of the manufacturing unit decreases, and the number of extending directions of the flexible cable sections decreases. Thus, a degree of freedom of the sheet layout is enhanced, and the efficient sheet layout is allowed. As a result, the number of flexible printed circuit boards obtained from one sheet can increase.
- Further, since manufacturing is performed in a unit of a partial flexible printed circuit board having an area size smaller than an original flexible printed circuit board, parts that should be discarded when a wiring failure or the like occurs decreases.
- As a result, the yield can be improved.
- Further, the partial flexible printed circuit board is cut from the sheet, and thereafter a predetermined number of partial flexible printed circuit boards are aligned so that a predetermined number of partial component mounting sections can be combined to configure a component mounting section and then fixed to a support plate. Thus, the flexible printed circuit board having the same function as the conventional art can be obtained.
- According to another embodiment of the present invention, by configuring the component mounting section of the flexible printed circuit board at two stages of an upper component mounting section and a lower component mounting section, the number of wirings formed in one partial component mounting section decreases. Thus, the wiring density can be alleviated, and a failure caused by wiring formation can decrease.
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FIG. 1(1) is a plan view of a flexible printed circuit board according to a first embodiment of the present invention, andFIG. 1(2) is a cross-sectional view taken along line A-A ofFIG. 1(1) . -
FIG. 2(1) is an enlarged plan view illustrating a state in which an electronic component is mounted on a component mounting section according to the first embodiment, andFIG. 2(2) is a cross-sectional view taken along line A-A ofFIG. 2(1) . -
FIG. 3A is a process cross-sectional view illustrating a method of manufacturing a flexible printed circuit board according to the first embodiment. -
FIG. 3B is a process cross-sectional view illustrating a method of manufacturing a flexible printed circuit board according to the first embodiment, subsequent toFIG. 3A . -
FIG. 4 is a plan view illustrating a plurality of partial flexible printed circuit boards, which is manufactured in a sheet, according to the first embodiment. -
FIG. 5 is a plan view of a partial flexible printed circuit board containing an unnecessary area, which is cut from a sheet, according to the first embodiment. -
FIG. 6 is an explanation view of an alignment method of a partial flexible printed circuit board according to the first embodiment. -
FIG. 7(1) is a plan view of a conventional flexible printed writing board, andFIG. 7(2) is a cross-sectional view taken along line A-A ofFIG. 7(1) . -
FIG. 8(1) is an enlarged plan view illustrating a state in which anelectronic component 45 is mounted on a component mounting section, andFIG. 8(2) is a cross-sectional view taken along line A-A ofFIG. 8(1) . -
FIG. 9 is a plan view of a plurality of conventional flexible printed circuit boards manufactured in a sheet. -
FIG. 10(1) is a plan view of a flexible printed circuit board according to a second embodiment of the present invention, andFIG. 10(2) is a cross-sectional view taken along line C-C ofFIG. 10(1) . -
FIG. 11(1) is an enlarged plan view illustrating a state in which an electronic component is mounted on a component mounting section according to the second embodiment, andFIG. 11(2) is a cross-sectional view taken along line C-C ofFIG. 11(1) . -
FIG. 12A is a process cross-sectional view illustrating a method of manufacturing a flexible printed circuit board according to the second embodiment. -
FIG. 12B is a process cross-sectional view illustrating a method of manufacturing a flexible printed circuit board according to the second embodiment, subsequent toFIG. 12A . -
FIG. 13 is a plan view illustrating a plurality of partial flexible printed circuit boards, which are manufactured in a sheet, according to the second embodiment. -
FIG. 14A is a plan view illustrating aligned partial flexible printed circuit boards according to the second embodiment. -
FIG. 14B is a plan view illustrating aligned partial flexible printed circuit boards according to the second embodiment. -
FIG. 15 is a cross-sectional view of a flexible printed circuit board according to a modification of the second embodiment. -
FIG. 16(1) is a plan view of a conventional flexible printed circuit board, andFIG. 16(2) is a plan view illustrating a plurality of conventional flexible printed circuit boards manufactured in a sheet. - Hereinafter, two embodiments according to the present invention will be described with reference to the accompanying drawings. In the drawings, components having the same function are denoted by the same symbols, and a description of components having the same symbol will not be repeated.
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FIG. 1(1) is a plan view of a flexible printedcircuit board 6 according to a first embodiment of the present invention.FIG. 1(2) is a cross-sectional view taken along line A-A ofFIG. 1(1) . As can be seen fromFIGS. 1(1) and 1(2) , the flexible printedcircuit board 6 includes left and right partial flexible printed circuit boards (partial FPC) 4 and asupport plate 5 and has the same function as the above described flexible printedcircuit board 44. - The two partial flexible printed
circuit boards 4 are fixed onto thesupport plate 5 in a state in which partialcomponent mounting sections 1A are aligned with high accuracy and combined to configure acomponent mounting section 1 for mounting an electronic component. At this point, in terms of a correspondence with the above described conventional flexible printedcircuit board 44, the partial flexible printedcircuit board 4 corresponds to left or right part of the flexible printedcircuit board 44 which is divided into two parts, keeping an internal wiring from being cut apart. - As illustrated in
FIG. 1(1) , the partial flexible printedcircuit board 4 includes a partialcomponent mounting section 1A, threeflexible cable sections 2 that extend in up, down, and left (or right) directions from the partialcomponent mounting section 1A,connection sections 3 respectively installed at leading ends of theflexible cable sections 2. - The partial
component mounting section 1A includes a plurality oflands 1a for being bonded with pins of an electronic component such as a sensor module. The partialcomponent mounting section 1A is left or right part of thecomponent mounting section 1 divided into two parts. Thus, thecomponent mounting section 1 is configured by combining the two partialcomponent mounting sections 1A. - The
flexible cable section 2 has flexibility and extends from the partialcomponent mounting section 1A in a predetermined direction. Theflexible cable section 2 has a plurality of fine wirings (not shown) that electrically connect thelands 1a withterminals 3a of theconnection section 3. - The
connection section 3 is, for example, a connector and has a plurality ofterminals 3a for connection with an external device. The plurality ofterminals 3a are electrically connected with thelands 1a associated therewith through the wirings of theflexible cable section 2, respectively. -
FIG. 2(1) is an enlarged plan view illustrating a state in which anelectronic component 7 such as a sensor module is mounted on thecomponent mounting section 1 including the twopartial mounting sections 1A fixed to thesupport plate 5.FIG. 2(2) is a cross-sectional view taken along line A-A ofFIG. 2(1) . As illustrated inFIG. 2(2) , a pin (solder ball) 7a of theelectronic component 7 is bonded to theland 1a. - As can be seen from
FIG. 2(2) , awiring 8 for electrically connecting theland 1a with the terminal 3a is installed betweenstep vias - The
electronic component 7 is, for example, a sensor module, and in this case, a signal of a sensor included in the sensor module is output from thepin 7a and transmitted to the terminal 3a through theland 1a, the step via 9, and thewiring 8. Theconnection section 3 in which theterminal 3a is installed may be connected with a printed circuit board (not shown) that processes a sensor signal. - The
support plate 5 fixes the left and right two partial flexible printedcircuit boards 4A so that the two partialcomponent mounting sections 1A can be combined to configure thecomponent mounting section 1. As illustrated inFIG. 2(2) , as thesupport plate 5, a coverlay having an insulatingfilm 5a and anadhesive material layer 5b thereon may be used. - As a material of the
support plate 5, an aramid resin film having an adhesive layer is preferably used. It is because the aramid resin film has small thermal expansion coefficient, and thus the aramid resin film does not nearly expand during a heating process for bonding the partial flexible printedcircuit boards 4 with thesupport plate 5 and can also retain flexibility. As thesupport plate 5, a material less expanding and contracting is preferably used in order to prevent a misalignment caused by the heating process during bonding and by a mechanical stress during handling. For example, a polyimide film or a liquid crystal polymer film may be used as the insulatingfilm 5a. - Next, a method of manufacturing the flexible printed
circuit board 6 according to the present embodiment will be described with reference to the drawings. -
FIGS. 3A and3B are process cross-sectional views illustrating a method of manufacturing the flexible printedcircuit board 6. - (1) First, prepared is a flexible double-side copper-clad laminated sheet 14 in which a
copper foil 12 and a copper foil 13 (each of which has, for exam, the thickness of 1 µm) are disposed on both sides of a flexible insulating base material (for example, the thickness of 25 µm) made of, for example, a polyimide film. Then, as illustrated inFIG. 3A(1) , on a predetermined sheet of the long double-side copper-clad laminated sheet 14, plating resistlayers cooper foil 12 positioned on an inner layer side and thecooper foil 13 positioned on an outer layer side, respectively. The plating resistlayers
The plating resistlayer 15B is a plating resist layer for forming a laser shielding mask, which functions when forming a step via hole by a laser process later, by the semi-additive technique. Further, the thickness of the plating resistlayer 15B is preferably about 1.2 to 2 times the thickness of a wiring layer to be formed. Here, the design thickness of the wiring is set to 10 µm, and the thickness of the plating resistlayer 15B is set to 15 µm. - (2) Next, an electrolyte copper plating process is performed on both sides of the double-side copper-clad laminated sheet 14 on which the plating resist
layers FIG. 3A(2) , electrolyte copper plating layers 16 and 17 are formed on portions of the copper foils 12 and 13 exposed through openings of the plating resistlayers layers
Through the processes up to this point, a double-sidecircuit base material 20 illustrated inFIG. 3A(2) is obtained.Conformal masks circuit base material 20. Theconformal mask 18 becomes a mask for forming an upper hole of the step via hole, and theconformal mask 19 becomes a mask for forming a lower hole of the step via hole. Theformal masks fine wirings 8 have been formed on the back side of the double-sidecircuit base material 20. 6wirings 8 are installed between theinner layer lands 1b, and a wiring pitch is, for example, 30 µm. - (3) Next, a single-side copper-clad
laminated sheet 23 having a copper foil 22 (for example, the thickness of 12 µm) is prepared on one side of the flexible insulating base material 21 (for example, a polyimide film having the thickness of 25 µm). As illustrated inFIG. 3A(3) , the single-side copper-cladlaminated sheet 23 is laminated on the back side of the double-sidecircuit base material 20 through an adhesive material layer 24 (for example, the thickness of 15 µm). Further, theadhesive material layer 24 is preferably formed by using an adhesive of which a flow index is small, such as prepreg of a low flow type or a bonding sheet.
A multi-layercircuit base material 25 illustrated inFIG. 3A(3) is obtained through the processes up to this point. - (4) Next, as illustrated in
FIG. 3A(4) , step viaholes 26 are formed by irradiating laser light onto the surface of the multi-layercircuit base material 25 and performing a conformal laser process using theconformal masks
In the laser process technique of the present process, a laser such as a UV-YAG laser, a carbon dioxide laser, or an excimer laser may be used. It is preferable to use the carbon dioxide laser in terms of advantages of high processing speed and productivity.
As a more detailed process condition, ML605GTXIII-5100 U2 available from Mitsubishi Electric Corporation was used as a carbon dioxide laser processing machine. The laser beam diameter was adjusted to 200 µm using a predetermined aperture or the like. The pulse width was 10 µsec, and the pulse energy was set to 5 mJ. The laser process was performed under the condition, an irradiation of 5 shots of a laser pulse for formation of one step via hole. - (5) Next, a desmear process and a conduction process are performed on the inside of the step via
hole 26, and thereafter the electrolyte copper plating process is performed on the whole surface of the multi-layercircuit base material 25 with the step via hole formed therein. As a result, as can be seen fromFIG. 3B(5) , an electrolytecopper plating layer 27 is formed on an inner wall (a side and a bottom) of the step viahole 26 and theelectrolyte copper layer 17. Accordingly, a step via 9 that functions as an interlayer conduction path is formed. Further, in order to secure interlayer conduction, the thickness of the electrolytecopper plating layer 27 is set to, for example, 15 to 20 µm.
In the plating process of the present process, since an open surface through the step viahole 26 is provided only at the top surface side of the multi-layercircuit base material 25, so-called single-side plating of performing the plating process only on the open surface of the step viahole 26 is performed. For this reason, the electrolyte copper plating layer is not formed on thecopper foil 22 on the back side of themulti-layer circuit material 25. The single-side plating may be implemented by forming a plating mask to cover thecooper foil 22 on the back side and thereafter performing the plating process, or may be implemented by installing a shielding plate in a plating device, a plating jig, or the like and thereafter performing the plating process. By performing the single-side plating rather than the double-side plating, an extra copper plating film is not formed on thecopper foil 22, and the film thickness of thecopper foil 22 can be prevented from increasing. As a result, a fine pattern having a land or the like can be formed by processing thecopper foil 22 that remains thin.
Thereafter, as illustrated inFIG. 3B(5) , anouter layer pattern 28 and theland 1a are formed by processing the electrolytecopper plating layer 27 and thecopper foil 22 into predetermined patterns, respectively, by a photofabrication technique. The photofabrication technique refers to a processing technique of patterning a processing target layer (copper foil etc.) into a predetermined pattern and includes a series of processes such as forming a resist layer on a processing target layer, exposing, developing, etching a processing target layer, and peeling off a resist layer.
At this point, the layout of the partial flexible printed circuit boards manufactured in the sheet will be described.
FIG. 4 is a plan view illustrating a plurality of partial flexible printed circuit boards manufactured in a sheet having the same size as the above describedsheet 48. As can be seen fromFIG. 4 , theflexible cable sections 2 of the partial flexible printedcircuit board 4 extends in three directions, that is, up, down, and left directions. On the other hand, in the above described flexible printedcircuit board 44, theflexible cable sections 42 extend in four directions, that is, up, down, left, and right directions. That is, the partial flexible printedcircuit board 4 is smaller than the flexible printedcircuit board 44 in the number of extending directions of the flexible cable sections.
Further, the area size of the partial flexible printedcircuit board 4 is about half the flexible printedcircuit board 44.
By arranging the partial flexible printedcircuit board 4 that is small in area size and in number of extending directions of the flexible cable sections inside thesheet 10, the efficient sheet layout can be achieved. As a result, the number of flexible printed circuit boards obtained from one sheet can increase. Specifically, as illustrated inFIG. 4 , in the case of the present embodiment, since 24 partial flexible printed circuit boards can be arranged from onesheet 10, it is possible to obtain a maximum of 12 flexible printedcircuit boards 4. Meanwhile, in the above described conventional example, as illustrated inFIG. 9 , at the most 9 flexible printed circuit boards can be obtained. - (6) Next, a plurality of partial flexible printed
circuit boards 4A are cut apart from thesheet 10 using a mold or the like. As illustrated inFIG. 5 , the cut partial flexible printedcircuit board 4A includes anarea 4B to be finally removed. That is, the partial flexible printedcircuit board 4 is one obtained by cut away thearea 4B along a dotted line ofFIG. 5 from the partial flexible printedcircuit board 4A. Further, the partial flexible printed circuit board may be cut out in a form containing noarea 4B. Further, from a point of view of productivity improvement, a plurality of partial flexible printedcircuit boards 4A manufactured in thesheet 10 are preferably collectively cut out.
A failure judgment is performed on the cut partial flexible printedcircuit board 4A to remove a failure such as a wiring failure. - (7) Next, as illustrated in
FIG. 6 andFIG. 3B(6) , the alignment of the two partial flexible printedcircuit boards 4A that have been judged as non-defective ones is performed by usingalignment targets circuit boards 4A and thesupport plate 5. The alignment targets 29 and 30 may include a guide hole, an alignment mark, or the like formed at a high degree of accuracy by a technique which will be described later.
The alignment of the present process needs be performed with high accuracy so that the two partialcomponent mounting sections 1A can configure thecomponent mounting section 1. Specifically, it depends on a type of an electronic component to be mounted, the size thereof, and a pitch between pins, but a degree of alignment accuracy of about ±50 µm is usually required.
For this reason, an apparatus having the same function as a chip mounter used during mounting of an electronic component is used for the alignment of the present process. That is, the alignment targets 29 and 30 are image-recognized, and the positions of the partial flexible printedcircuit boards 4A are adjusted so that the alignment targets 29 and 30 can overlap each other using the result.
Thealignment target 29 is formed by recognizing apredetermined land 1a (for example, a land 1ae close to a joint part of the partialcomponent mounting sections 1A, seeFIG. 6 ) and performing the laser process based on the position of the land 1ae. By doing so, a required accuracy of alignment can be secured. Further, as illustrated inFIG. 6 , thealignment target 29 is formed in thearea 4B, but its formation position is not limited to thearea 4B, for example, it may be the partialcomponent mounting section 1A.
Thealignment target 30 of thesupport plate 5 is formed, for example, at a predetermined position of thesupport plate 5 by a mold or the like.
As an alternative technique, the alignment may be performed usingpredetermined lands 1a as the alignment target without using the alignment targets 29 and 30. That is, the positions of thelands 1a in the left and right two partial flexible printedcircuit boards 4A are image-recognized, and the relative positions of the two partial flexible printedcircuit boards 4A are adjusted so that both can have a predetermined positional relationship (for example, the distance between thelands circuit boards 4A may be used.
Meanwhile, as a method of forming the alignment target 29 (the guide hole), the following method can be considered. That is, by using a mold configured to have a guide hole formed therein, guide holes of the partial flexible printedcircuit boards 4A may be collectively formed at the same time when collectively cutting a plurality of partial flexible printedcircuit boards 4A out from thesheet 10. According to this method, since the guide holes are collectively formed, productivity increases as compared with the above described method of separate formation. However, for example, when the partial flexible printedcircuit board 4A is large, due to a variation in expansion and contraction of the partial flexible printedcircuit boards 4A manufactured in thesheet 10, the position of the guide hole may be displaced from a predetermined position, and so required alignment accuracy not be secured. However, in order to secure stable alignment accuracy that does not depend on the size or the shape of the partial flexible printedcircuit board 4A, it is preferable to form the alignment target individually on the partial flexible printedcircuit board 4A which is cut out from the sheet as described above. - (8) Next, as illustrated in
FIG. 3B (7) , the two partial flexible printedcircuit boards 4A are fixed onto thesupport plate 5. As a fixing method, for example, thermocompression bonding is performed in the case of using a coverlay as thesupport plate 5. - Thereafter, an unnecessary part including the
area 4B in thesupport plate 5 is removed using a mold or the like. Further, thealignment target 29 may be used in a process of removing the unnecessary area. - The flexible printed
circuit board 6 illustrated inFIG. 1 is obtained through the above described processes. - As described above, the sheet layout is performed in units of partial flexible printed circuit boards, each unit includes a partial component mounting section that is one of a predetermined number (2 in the present embodiment) of partial component mounting sections divided from one component mounting section. Thus, the area size of a manufacturing unit decreases, and the number of extending directions of the flexible cable section decreases. For this reason, the efficient layout can be achieved. As a result, compared with the conventional art, it is possible to increase the number of flexible printed circuit boards that can be obtained from one sheet. Further, it is possible to reduce sheet materials discarded. Thus, it is possible to reduce the manufacturing cost per flexible printed circuit board.
- Further, by using, as a manufacturing unit, the partial flexible printed circuit board having the area size smaller than the original flexible printed circuit board, when a formation failure of a wiring or the like occurs, it is possible to reduce an affected range thereof compared to the conventional art. Thus, according to the present embodiment, the yield can improve compared to the conventional art.
- For example, in the conventional art, when a foreign substance defect occurs in 10 spots in one sheet and thus 10 flexible printed circuit boards out of 20 flexible printed circuit boards manufactured from the sheet are defective, the yield is 50%. However, according to the method of the present embodiment, when a foreign substance defect occurs in 10 spots in one sheet and thus 10 partial flexible printed circuit boards out of 40 partial flexible printed circuit boards manufactured in the sheet are defective, the remaining 30 partial flexible printed circuit boards are not defective. Since 15 flexible printed circuit boards are obtained by combining the non-defective partial flexible printed circuit boards, the yield is 75%. That is, in this case, it is possible to reduce a percent defective by half from 50% to 25%.
- In the above described example, when the number of non-defective partial flexible printed circuit boards is an odd number, one partial flexible printed circuit board remains unused. However, in actual manufacturing, since the non-defective flexible printed circuit boards that are cut out from a plurality of sheets can be used in combination, the high yield can be maintained.
- The first embodiment of the present invention has been described above, but the structure of the flexible printed circuit board according to the present embodiment is not limited to the above example. That is, a flexible printed circuit board to which the present embodiment can be applied may not have the step via structure or may have a single layer structure.
- Further, the
support plate 5 may be formed on the whole back surface of the partial flexible printedcircuit board 4 or may be formed only on the back side of thecomponent mounting section 1. - Dividing the
component mounting section 1 is not limited to dividing thecomponent mounting section 1 into two, left and right, partialcomponent mounting sections 1A. Thecomponent mounting section 1 may be divided into two or more in light of the shape of the flexible printed circuit board, the area size of the fine wiring area, the yield, and the like. For example, in the case of the flexible printedcircuit board 6 illustrated inFIG. 1 , thecomponent mounting section 1 may be divided using a set ofpins 7a corresponding to oneconnection section 3 as a unit. In this case, thecomponent mounting section 1 is divided into 6 partial component mounting sections. - Before describing a flexible printed circuit board according to a second embodiment, the flexible printed circuit board of a conventional manufacturing method that is functionally the same as the flexible printed circuit board according to the second embodiment will be described.
FIG. 16(1) is a plan view of a flexible printedcircuit board 144 according to a conventional manufacturing method. Unlike the flexible printedcircuit board 44 described in the first embodiment, the flexible printedcircuit board 144 does not include theflexible cable sections 42 that extend from left and right terminals of thecomponent mounting section 41. That is, as illustrated inFIG. 16(1) , in the flexible printedcircuit board 144, a total of 4flexible cable sections 42 extend from an upper end and a lower end of thecomponent mounting section 41. A cross-sectional view taken along line A-A ofFIG. 16(1) is the same asFIG. 7(2) . -
FIG. 16(2) is a plan view of asheet 148 having 9 flexible printedcircuit boards 144 manufactured based on a predetermined layout. As can be seen fromFIG. 16(2) , since the area size of the flexible printedcircuit board 144 is large and theflexible cable section 42 is disposed to extend in up and down directions from thecomponent mounting section 41, a degree of freedom of the sheet layout is restricted. For this reason, it is difficult to arrange the flexible printedcircuit boards 144 in an efficient fashion within thesheet 148. - Next, the flexible printed circuit board according to the second embodiment will be described.
FIG. 10(1) is a plan view of a flexible printedcircuit board 106 according to the second embodiment, andFIG. 10(2) is a cross-sectional view taken along line C-C ofFIG. 10(1) . - As can be seen from
FIGS. 10(1) and10(2) , the flexible printedcircuit board 106 includes asupport plate 5, left and right two partial flexible printedcircuit boards 104a fixed to thesupport plate circuit boards 104b stacked on the partial flexible printedcircuit boards 104a through an anisotropicconductive layer 99. - The partial flexible printed
circuit boards component mounting sections 101A,flexible cable sections 102 that extend from the partialcomponent mounting sections 101A,connection sections 103 disposed at leading ends of theflexible cable sections 102, respectively. In the following description, when the partial flexible printedcircuit board 104a and the partial flexible printedcircuit board 104b need not be discriminated from each other, they are described as the partial flexible printed circuit board 104. - As illustrated in
FIG. 10(2) , a total of 4 partialcomponent mounting sections 101A which are included in the two partial flexible printedcircuit boards 104a and the two partial flexible printedcircuit boards 104b are combined in a horizontal direction and a vertical direction to configure thecomponent mounting section 101. That is, a lower component mounting section is configured by arranging the partialcomponent mounting sections circuit boards 104a on the same plane, and an upper component mounting section is configured by arranging the partialcomponent mounting sections circuit boards 104b on the same plane. Thecomponent mounting section 101 is configured such that the upper component mounting section is stacked on the lower component mounting section.Lands 1a of the upper component mounting section and the lower component mounting section are the same in arrangement (number and pitch) as thelands 41a of thecomponent mounting section 41. - The partial
component mounting section 101A includes a plurality oflands 1a for being bonded with pins of an electronic component such as a sensor module on its top surface. Theflexible cable section 102 has flexibility, extends from the partialcomponent mounting section 101A in a predetermined direction, and has a plurality of fine wirings (not shown) that electrically connect thelands 1a withterminals 103a of theconnection section 103. The connection section 103 (for example, a connector) has a plurality ofterminals 103a for connection with an external device. The plurality ofterminals 103a are electrically connected with the correspondinglands 1a respectively through the wirings of theflexible cable section 102, respectively. -
FIG. 11(1) is an enlarged plan view illustrating a state in which anelectronic component 107 is mounted on thecomponent mounting section 101 of the flexible printedcircuit board 106.FIG. 11(2) is a cross-sectional view taken along line C-C ofFIG. 11(1) . Apin 107a of theelectronic component 107 is bonded to theland 1a of the partial flexible printedcircuit board 104b. The partial flexible printed circuit board 104 has a step via 9 and afine wiring 108. Thewiring 108 is a wiring for electrically connecting theland 1a with the terminal 103a of theconnection section 103 and disposed between thestep vias - An anisotropic
conductive layer 99 for bonding the partial flexible printedcircuit board 104a with the partial flexible printedcircuit board 104b is formed by heating an anisotropicconductive film 98 in whichconductive particles 99a are dispersed. The anisotropicconductive layer 99 has anisotropic conductivity and has both conductivity and dielectric property. That is, as can been seen fromFIG. 11(2) , theconductive particles 99a included in the anisotropicconductive layer 99 allow an electrical connection in a vertical direction but an electrical connection in a horizontal direction is hindered. For this reason, theland 1a of the partial flexible printedcircuit board 104a is electrically connected with the step via 9 of the flexible printedcircuit board 104b positioned directly thereon, but an insulated state is maintained on the remaining portions. That is, theland 1a of the partial flexible printedcircuit board 104b is electrically connected with theland 1a of the flexible printedcircuit board 104a positioned directly thereon through theconductive particle 99a and the step via 9. - Here, a description will be made in connection with the flow of a signal between the
pin 107a of theelectronic component 107 and theconnection section 103 of the flexible printedcircuit board 106. A signal flow path is greatly divided into two. In the case of a first path, a signal output from thepin 107a of theelectronic component 107 passes through theland 1a, the step via 9, and thewiring 108 formed in the partial flexible printedcircuit board 104b and is transmitted to the terminal 103a through a wiring inside theflexible cable section 102 extending from the partialcomponent mounting section 101A of the partial flexible printedcircuit board 104b. In the case of a second path, it passes through the partial flexible printedcircuit board 104a. That is, a signal output from thepin 107a passes through theland 1a and the step via 9 formed in the partial flexible printedcircuit board 104b, passes through theland 1a, the step via 9, and thewiring 8 formed in the partial flexible printedcircuit board 104a, and is transmitted to the terminal 103a through a wiring inside theflexible cable section 102 extending from the partialcomponent mounting section 101A of the partial flexible printedcircuit board 104b. - When the
electronic component 107 is the sensor module, thepin 107a and the terminal 103a have a one-to-one correspondence relationship. In this case, inFIG. 11(2) , one of the vertically arrangedstep vias 9 is provided as a dummy and thus is not actually used. - As can be understood from the above description, the flexible printed
circuit board 106 has the same function as the above described flexible printedcircuit board 144. - Since the flexible printed
circuit board 106 is configured by laminating the partial flexible printed circuit boards 104 in two stages including upper and lower stages, the number of partial component mounting sections is as twice as that of the first embodiment. Thus, the number of wirings formed in one partial component mounting section decreases, and so the wiring density can be alleviated. Specifically, in the first embodiment, 6wirings 8 are disposed between the step vias 9 (seeFIG. 2(2) ), but in the second embodiment, as illustrated inFIG. 11(2) ,3 wirings that are half are disposed betweens thestep vias 9. In terms of a numerical value as an example, in the case where 6 wirings are installed between the inner layer lands 1b disposed at an interval of 200 µm, a wiring interval in the present embodiment is 60 µm, whereas it is 30 µm in the - Next, a method of manufacturing the flexible printed
circuit board 106 according to the present embodiment will be described with reference toFIGS. 12A to 14B . - (1) The partial flexible printed
circuit boards FIG. 12A(1) are obtained through the same processes described with reference toFIGS. 3A(1) to 3A(4) andFIG. 3B(5) in the first embodiment. One of different points from the first embodiment is that thewiring 108 is larger in pitch than thewiring 8. Another different point is the sheet layout of the partial flexible printedcircuit boards FIG. 13 .
FIG. 13 is a plan view illustrating the partial flexible printedcircuit boards sheet 100 of the same size as the above describedsheet 148. As can be seen fromFIG. 13 , oneflexible cable section 102 extends from one partial flexible printedcircuit board circuit boards flexible cable section 102 and thus do not have the same shape.
Further, instead of manufacturing both the partial flexible printedcircuit board 104a and the partial flexible printedcircuit board 104b in one sheet as illustrated inFIG. 13 , the partial flexible printedcircuit board 104a may be manufactured in one sheet, and the partial flexible printedcircuit board 104a may be manufactured in another sheet.
Compared to the flexible printedcircuit board 144, the partial flexible printed circuit board 104 is small in area size and number of extending directions of the flexible cable sections. For this reason, it allows an efficient sheet layout of the partial flexible printed circuit boards 104 in thesheet 100. As a result, it is possible to increase the number of flexible printed circuit boards obtained from one sheet. Specifically, as illustrated inFIG. 13 , 23 partial flexible printedcircuit boards circuit boards 104b can be arranged within one sheet. One flexible printedcircuit board 106 is configured with the two partial flexible printedcircuit boards 104a and the two partial flexible printedcircuit boards 104b. For this reason, a maximum of 11 flexible printedcircuit boards 106 can be obtained from one sheet. Meanwhile, in the conventional example illustratedFIG. 16 , a maximum of 9 flexible printed circuit boards can be obtained. - (2) Next, the partial flexible printed circuit board 104 is cut out from the
sheet 100 using a mold or the like. As can be seen fromFIG. 14A , the cut partial flexible printed circuit board 104 may have thearea 104B to be provided with the alignment target 129 thereon. Thearea 104B is finally removed as will be described later. After cut out from the sheet, the partial flexible printed circuit board 104 is subjected to a failure judgment, and a defective one is removed. In the present embodiment, since thewiring 108 is as about twice thick as thewiring 8, a probability that a failure is caused by wiring formation can decrease by half. Further, as necessary, after the partial flexible printed circuit board 104 is cut out, surface processing such as solder plating, nickel plating or gold plating on a terminal surface such as a land section and forming a protective photo-solder resist layer on a part where soldering is unnecessary, and an outward shape processing are performed. - (3) Next, as illustrated in
FIG. 12A(2) , the partialcomponent mounting sections circuit boards 104a are combined and aligned to configure a lower component mounting section.
For example, the alignment is performed using the alignment targets 129 and 130 respectively formed on the partial flexible printedcircuit board 104a and thesupport plate 5 such that the alignment targets 129 and 130 can match with each other. The alignment targets 129 and 130 are guide holes or alignment marks formed with high accuracy and formed in the same manner as described in the first embodiment.FIG. 14A is a plan view of the partial flexible printedcircuit boards 104a aligned on thesupport plate 5. As illustrated inFIG. 14A , the alignment target 129 of the partial flexible printedcircuit board 104a matches with the alignment target 130 of thesupport plate 5.
Further, as an alternative alignment method, without using the alignment targets 129 and 130, the alignment may be performed by image-recognizing the positions of predetermined lands (for example, lands 1ae illustrated inFIG. 14A ) in the left and right two partial flexible printedcircuit boards 104a and positioning them to be in a predetermined position relationship. - (4) Next, the aligned two flexible printed
circuit boards 104a are placed on thesupport plate 5 and fixed by thermocompression bonding or the like. Thesupport plate 5 supports at least the lower component mounting section of the partial flexible printedcircuit boards 104a.
A lower flexible printedcircuit board 131 illustrated inFIG. 12A(3) is obtained through the processes up to this point. - (5) Next, as illustrated in
FIG. 12B(4) , the partialcomponent mounting sections circuit boards 104b are combined and aligned to configure an upper component mounting section.
For example, the alignment is performed using alignment targets respectively formed on the partial flexible printedcircuit board 104b and the anisotropic conductive film (ACF) 98 such that the alignment targets can match with each other. As an alternative alignment method, the alignment may be performed by image-recognizing the positions of predetermined lands (for example, lands 1ae illustrated inFIG. 14B ) in the left and right two partial flexible printedcircuit boards 104b and positioning them to be in a predetermined position relationship. - (6) Next, the aligned two flexible printed
circuit boards 104b are attached and fixed onto the anisotropic conductive film 98 (for example, a thickness of 50 µm). The anisotropicconductive film 98 supports at least the upper component mounting section of the partial flexible printedcircuit boards 104b.
At this point, ANISOLM AC-200 (available from Hitachi Chemical Co., Ltd.) of a high-heat resistance specification was used as the anisotropicconductive film 98 under the assumption that a reflow process that is a high temperature process is performed when theelectronic component 107 is mounted.
An upper flexible printedcircuit board 132 illustrated inFIG. 12B(5) is obtained through the processes up to this point. - (7) Next, as illustrated in
FIG. 14B , the upper flexible printedcircuit board 132 is aligned with the lower flexible printedcircuit board 131. The alignment is performed such that the upper component mounting section of the upper flexible printedcircuit board 132 is positioned directly on the lower component mounting section of the lower flexible printedcircuit board 131. For example, the alignment is preferably performed such the alignment target 129 of the lower flexible printedcircuit board 131 can match with the alignment target 130 of the upper flexible printedcircuit board 132. - (8) Next, after the upper flexible printed
circuit board 132 is placed on the lower flexible printedcircuit board 131, heating and pressurizing are performed. Here, heating and pressurizing have been performed for 5 seconds under the condition of 220 °C in temperature and 4 MPa in pressure. As a result, as illustrated inFIG. 12B(6) , the anisotropicconductive film 98 is melt to become an anisotropicconductive film 99 that fills the step via 9 of the partial flexible printedcircuit board 104b and attaches the upper flexible printedcircuit board 132 to the lower flexible printedcircuit board 131. As illustrated inFIG. 12B(6) , interlayer conduction is obtained by theconductive particles 99a between theland 1a of the partial flexible printedcircuit board 104a and the step via 9 of the partial flexible printedcircuit board 104b. That is, the present process produces thecomponent mounting section 101 which includes the upper component mounting section and the lower component mounting section and in which theland 1a of the lower component mounting section is electrically connected with theland 1a of the upper component mounting section positioned directly thereon through theconductive particles 99a and the step via 9. - (9) Next, an unnecessary area such as the
area 104B is removed using a mold or the like, so that the flexible printedcircuit board 106 illustrated inFIG. 10 is obtained. - Thereafter, as described with reference to
FIG. 11 , theelectronic component 107 such as the sensor module is mounted on the flexible printedcircuit board 106. In the present embodiment, since the anisotropicconductive film 98 of the high-heat resistance specification is used, the electronic component has been mounted by the reflow process. - In the case of using a general anisotropic conductive film that does not have the high-heat resistance specification, if the high temperature process such as the reflow process is used, the process temperature exceeds a heat-resistance temperature of the anisotropic conductive film. Thus, in this case, it is necessary to use a method of mounting the electronic component at a relatively low temperature. For example, an ultrasonic connection technique may be used. In this technique, the
pin 107a is connected with theland 1a such that gold plating or the like is performed on thepin 107a and theland 1a, theelectronic component 107 is placed on the flexible printedcircuit board 106, and then plating metal is heated by ultrasonic vibration. - Further, the step via 9 may be a filled via, that is, a step via hole filled with a conductor.
FIG. 15 is a cross-sectional view of a flexible printed circuit board in which a filed via 97 is formed on the upper flexible printedcircuit board 132. With such a filled via structure, flatness in the back surface of the partial flexible printedcircuit board 104b (a lower side inFIG. 15 ) improves. For this reason, as can be seen fromFIG. 15 , it is possible to increase the number of theconductive particles 99a that are present between anopen surface 97a of the filled via 97 and theland 1a of the lower flexible printedcircuit board 131 directly below the open surface of the field via. As a result, connection reliability of an interlayer conduction path can improve. Further, as a method of forming the filled via 97, a via fill plating technique using a plating solution containing a special additive or a technique of filling a step via hole with a conductive paste may be used. - Further, in the present embodiment, the component mounting section has been divided into two layers including upper and lower layers, but the present invention is not limited thereto. The flexible printed circuit board may be configured by laminating three or more partial flexible printed circuit boards.
- As described above, according to the second embodiment, the same effect as in the first embodiment is obtained. Further, by employing the laminate structure for the component mounting section, the number of partial
component mounting sections 101A increases, leading to a decrease in the number of wirings formed in one partial component mounting section, which results in a reduction in the wiring density. As a result, a failure caused by formation of fine wirings can decrease by half. In actual manufacturing, since indefective partial flexible printed circuit boards that are cut out from a plurality of sheets can be combined, the yield can increase further. - The second embodiment according to the present invention has been described above, but the structure of the flexible printed circuit board according to the present invention is not limited to the above embodiments.
- The number of flexible cable sections and the direction extending from the component mounting section are not limited to the above described embodiment.
- Further, without disposing the connection section 3 (103), a configuration in which an additional component mounting section (for example, on which a semiconductor integrated circuit processing a signal of the sensor, module mounted on the component mounting section 1(101), is mounted) may be integrally connected with the flexible cable section may be used.
- Further, the interlayer conduction path for obtaining interlayer conduction is not limited to the step via but may be a different type of via or a through via. Those who skilled in the art can expect an additional effect or various modifications of the present invention, but aspects of the present invention are not limited to the above described embodiments. Various additions, changes, and partial deletions can be made in a range not departing the conceptual spirit and purpose of the present invention derived from matters set forth in claims and equivalents.
-
- 1, 41, 101
- component mounting section
- 1A, 101A
- partial component mounting section
- 1a, 1ae, 41a
- land
- 1b, 41b
- inner land
- 2, 42, 102
- flexible cable section
- 3, 43, 103
- connection section
- 3a, 43a, 103a
- terminal
- 4,4A, 104a, 104b, 104
- partial flexible printed circuit board
- 48, 104B
- area
- 5
- support plate
- 5a
- insulating film
- 5b
- adhesive material layer
- 6, 44, 106, 144
- flexible printed circuit board
- 7, 45, 107
- electronic component
- 7a, 45a, 107a
- pin
- 8, 46, 108
- wiring
- 9, 47
- step via
- 10, 48, 100, 148
- sheet
- 11, 21
- flexible insulating base material
- 12, 13, 22
- copper foil
- 14
- dual-side copper-clad laminated sheet
- 15A. 15B
- plating resist layer
- 16, 17, 27
- electrolyte copper plating layer
- 18, 19
- conformal mask
- 20
- dual-side circuit base material
- 23
- single-side cooper-clad laminated sheet
- 24
- adhesive material layer
- 25
- multi-layer circuit base material
- 26
- step via hole
- 28
- outer layer pattern
- 29, 30, 129, 130
- alignment target
- 97
- filled via
- 97a
- open surface
- 98
- anisotropic conductive film
- 99
- anisotropic conductive layer
- 99a
- conductive particles
- 131
- lower flexible printed circuit board
- 132
- upper flexible printed circuit board
Claims (6)
- A method of manufacturing a flexible printed circuit board (106), comprising:manufacturing a plurality of first partial flexible printed circuit boards (104a) each of which includes a first partial component mounting section (101A) having a first land (1a) formed on a surface thereof and a flexible cable section (102) extending from the first partial component mounting section (101A);manufacturing a plurality of second partial flexible printed circuit boards (104b) each of which includes a second partial component mounting section (101A) having a second land (1a) formed on a surface thereof and an interlayer conduction path electrically connected with the second land (1a) and a flexible cable section (102) extending from the second partial component mounting section (101A);forming a lower flexible printed circuit board (131) by performing an alignment so that the first partial component mounting sections (101A) of the two first partial flexible printed circuit boards (104a) configure a lower component mounting section and then fixing the two first partial flexible printed circuit boards (104a) onto a support plate (5);forming an upper flexible printed circuit board (132) by performing an alignment so that the second partial component mounting sections (101A) of the two second partial flexible printed circuit boards (104b) configure an upper component mounting section and then fixing the two second partial flexible printed circuit boards (104b) onto an anisotropic conductive film (98) containing a conductive particle (99a) therein; andforming a component mounting section (101) in which the upper component mounting section and the lower component mounting section are included and the first land is electrically connected with the second land positioned directly thereon through the conductive particle (99a) and the interlayer conduction path, by placing the upper flexible printed circuit board (132) on the lower flexible printed circuit board (131) and performing heating pressurizing.
- The method of manufacturing the flexible printed circuit board (106) according to claim 1,
wherein the first partial flexible printed circuit board (104a) and the second partial flexible printed circuit board (104b) are manufactured within the same sheet (100). - The method of manufacturing the flexible printed circuit board (106) according to claim 1 or 2,
wherein the alignment for configuring the lower component mounting section includes the steps of:forming first and second alignment targets (129,130) in the first partial flexible printed circuit board (104a) and the support plate (5), respectively;image-recognizing the first and second alignment targets (129,130); andadjusting positions of the first partial flexible printed circuit boards (104a) in such a manner that the first alignment target (129) matches with the second alignment target (130), using the result of the image-recognition;wherein the alignment for configuring the upper component mounting section includes the steps of:forming third and fourth alignment targets (129,130) in the second partial flexible printed circuit board (104b) and the anisotropic conductive film (98), respectively;image-recognizing the third and fourth alignment targets (129,130) and;adjusting positions of the second partial flexible printed circuit boards (104b) in such a manner that the third alignment target (129) matches with the fourth alignment target (130), using the result of the image-recognition. - The method of manufacturing the flexible printed circuit board (106) according to claim 1 or 2,
wherein the alignment for configuring the lower component mounting section includes the steps of:image-recognizing a predetermined land (1ae) of the first partial component mounting section (101A); andadjusting a position of the first partial flexible printed circuit board (104a) with reference to a position of the land (1ae);wherein the alignment for configuring the upper component mounting section includes the steps of:image-recognizing a predetermined land (1ae) of the second partial component mounting section (101A); andadjusting a position of the second partial flexible printed circuit board (104b) with reference to a position of the land (1ae). - A flexible printed circuit board (106), comprising:a support plate (5);a first partial flexible printed circuit board (104a) that includes a first partial component mounting section (101A) having a first land (1a) formed on a surface thereof and a first interlayer conduction path electrically connected with the first land, and a flexible cable section (102) extending from the first partial component mounting section (101A);a second partial flexible printed circuit board (104b) that includes a second partial component mounting section (101A) having a second land (1a) formed on a surface thereof and a second interlayer conduction path electrically connected with the second land, and a flexible cable section (102) extending from the second partial component mounting section (101A);wherein a lower component mounting section, which is configured such that the two first partial component mounting sections (101A) are arranged on the same plane, being fixed onto the support plate (5); an upper component mounting section, which is configured such that the two second partial component mounting sections (101A) are arranged on the same plane, being stacked on the lower component mounting section through an anisotropic conductive layer (99) having a conductive particle (99a); and the first land being electrically connected with the second land positioned directly thereon through the conductive particle and the second interlayer conduction path.
- The flexible printed circuit board (106) according to claim 5,
wherein a wiring for electrically connecting the first interlayer conduction path with a terminal of a connection section (103) disposed at a leading end of the flexible cable section (102) extending from the first partial component mounting section is disposed between the neighboring first interlayer conduction paths, and
a wiring for electrically connecting the second interlayer conduction path with a terminal of a connection section (103) disposed at a leading end of the flexible cable section (102) extending from the second partial component mounting section is disposed between the neighboring second interlayer conduction paths.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2010167411 | 2010-07-26 | ||
EP10854247.3A EP2600701B1 (en) | 2010-07-26 | 2010-12-07 | Flexible printed circuit board and method of manufacturing thereof |
Related Parent Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP10854247.3A Division-Into EP2600701B1 (en) | 2010-07-26 | 2010-12-07 | Flexible printed circuit board and method of manufacturing thereof |
EP10854247.3A Division EP2600701B1 (en) | 2010-07-26 | 2010-12-07 | Flexible printed circuit board and method of manufacturing thereof |
Publications (1)
Publication Number | Publication Date |
---|---|
EP3013128A1 true EP3013128A1 (en) | 2016-04-27 |
Family
ID=45529580
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP15197991.1A Withdrawn EP3013128A1 (en) | 2010-07-26 | 2010-12-07 | Flexible printed circuit board and method of manufacturing the same |
EP10854247.3A Active EP2600701B1 (en) | 2010-07-26 | 2010-12-07 | Flexible printed circuit board and method of manufacturing thereof |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP10854247.3A Active EP2600701B1 (en) | 2010-07-26 | 2010-12-07 | Flexible printed circuit board and method of manufacturing thereof |
Country Status (7)
Country | Link |
---|---|
US (3) | US9185802B2 (en) |
EP (2) | EP3013128A1 (en) |
JP (1) | JP5475135B2 (en) |
CN (1) | CN102656956B (en) |
HK (1) | HK1171901A1 (en) |
TW (1) | TWI543681B (en) |
WO (1) | WO2012014339A1 (en) |
Families Citing this family (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN104690420B (en) * | 2013-12-05 | 2016-08-17 | 大族激光科技产业集团股份有限公司 | FPC edges of boards positioning and processing method based on digital CCD |
JP6307936B2 (en) * | 2014-02-28 | 2018-04-11 | オムロン株式会社 | Flexible printed circuit board, surface light source device, display device, and electronic device |
JP6187776B2 (en) * | 2014-12-12 | 2017-08-30 | カシオ計算機株式会社 | Electronics |
WO2016151762A1 (en) * | 2015-03-24 | 2016-09-29 | オリンパス株式会社 | Electronic circuit module |
CN105517339A (en) * | 2015-12-31 | 2016-04-20 | 武汉华星光电技术有限公司 | Electronic terminal |
WO2017183461A1 (en) | 2016-04-20 | 2017-10-26 | Jsr株式会社 | Polymer, composition, molded article, cured product, and laminate |
EP3683050A4 (en) | 2017-09-15 | 2021-06-23 | JSR Corporation | High-frequency circuit laminate, method for manufacturing same, and b-stage sheet |
KR20200054194A (en) | 2017-09-15 | 2020-05-19 | 제이에스알 가부시끼가이샤 | Circuit board |
JP7232413B2 (en) * | 2019-03-15 | 2023-03-03 | 株式会社リコー | Bonding substrate, liquid ejection head, liquid ejection unit, and liquid ejection device |
CN110536556A (en) * | 2019-09-02 | 2019-12-03 | 达格测试设备(苏州)有限公司 | The connection method of flexible circuit board hot pressing precision locating tool and flexible circuit board |
TWI749724B (en) * | 2020-08-21 | 2021-12-11 | 和碩聯合科技股份有限公司 | Electronic circuit system |
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-
2010
- 2010-12-07 EP EP15197991.1A patent/EP3013128A1/en not_active Withdrawn
- 2010-12-07 US US13/138,752 patent/US9185802B2/en active Active
- 2010-12-07 JP JP2012526270A patent/JP5475135B2/en active Active
- 2010-12-07 CN CN201080043998.3A patent/CN102656956B/en active Active
- 2010-12-07 EP EP10854247.3A patent/EP2600701B1/en active Active
- 2010-12-07 WO PCT/JP2010/071898 patent/WO2012014339A1/en active Application Filing
-
2011
- 2011-07-26 TW TW100126346A patent/TWI543681B/en active
-
2012
- 2012-12-07 HK HK12112674.4A patent/HK1171901A1/en unknown
-
2015
- 2015-09-29 US US14/868,609 patent/US10383224B2/en active Active
- 2015-09-29 US US14/868,619 patent/US9655239B2/en active Active
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US5086652A (en) * | 1991-02-25 | 1992-02-11 | Fel-Pro Incorporated | Multiple pad contact sensor and method for measuring contact forces at a plurality of separate locations |
WO2004064143A1 (en) * | 2003-01-08 | 2004-07-29 | Lg Cable Ltd. | Method of microelectrode connection and connected structure of use threof |
JP2007128970A (en) | 2005-11-01 | 2007-05-24 | Nippon Mektron Ltd | Manufacturing method of multilayer wiring board having cable section |
JP2008235745A (en) | 2007-03-23 | 2008-10-02 | Epson Imaging Devices Corp | Method for manufacturing sheet with which two or more unit substrate is connected and sheet to which two or more unit substrate is connected |
JP2010040949A (en) | 2008-08-07 | 2010-02-18 | Nippon Mektron Ltd | Method of replacing unit wiring board of aggregate board, and aggregate board |
Also Published As
Publication number | Publication date |
---|---|
JPWO2012014339A1 (en) | 2013-09-09 |
EP2600701B1 (en) | 2017-03-29 |
US20120175154A1 (en) | 2012-07-12 |
TWI543681B (en) | 2016-07-21 |
US10383224B2 (en) | 2019-08-13 |
CN102656956B (en) | 2015-02-18 |
US9655239B2 (en) | 2017-05-16 |
US9185802B2 (en) | 2015-11-10 |
US20160044784A1 (en) | 2016-02-11 |
US20160044797A1 (en) | 2016-02-11 |
TW201230907A (en) | 2012-07-16 |
CN102656956A (en) | 2012-09-05 |
EP2600701A1 (en) | 2013-06-05 |
WO2012014339A1 (en) | 2012-02-02 |
HK1171901A1 (en) | 2013-04-05 |
JP5475135B2 (en) | 2014-04-16 |
EP2600701A4 (en) | 2015-05-06 |
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